A single method for the inversion of anisotropic data sets with application to structural studies

Compaction and Failure in High Porosity Carbonates: Mechanical Data and Microstructural Observations

“…P-wave velocity was measured on core samples in different directions following the method described in LOUIS et al (2004). A set of 21 independent P-wave velocity measurements was obtained on samples cored in three orthogonal directions.…”

Determination of the anisotropy of elastic waves monitored by a sparse sensor network

“…It considers a medium, in which there is only one direction of maximum and minimum velocities, which, moreover, are mutually perpendicular. This is a significant simplification compared to the most general condition of material anisotropy (see also [20]). In case of rocks, the resultant velocity anisotropy is a complicated function of the lattice, grains shape, their preferred orientations and modal composition, and as well as the effects of cracks and pores In general, the mechanical properties are controlled by effective elastic parameters, which lead to the simplification of velocity anisotropy and this can correspond to the model of the triaxial velocity ellipsoid.…”

“…In a suitable sensors configuration, the different trajectories allow a sufficient directional coverage of the sample. One of the methods of processing travel times is to establish an anisotropic velocity model by approximating the directional dependence of velocity with a triaxial velocity ellipsoid [20]. The changes of the velocity ellipsoid in the course of the loading experiment may provide evidence, e.g., of the initial closing of the primary microcracks running perpendicular to the acting load, and after exceeding the local ultimate strength may monitor the fracturing process of the material.…”

Expedition 316 methods

“…From these values, a best fitting ellipsoidal function (which requires a minimum of six measurements in different directions) was calculated following the method of Louis et al (2004). Such an analysis can provide both anisotropy values and 3-D principal directions of the dominant microstructural feature (preferential alignment of matrix components, crack network, solution cleavage surfaces, etc.…”